1. Field of the Invention
The present invention concerns a lock-up clutch for a hydrokinetic coupling device including improved connection means.
The invention concerns more particularly a lock-up clutch for a hydrokinetic coupling device, in particular for automobile vehicles, including, around a main axis, at least one first element having a first friction surface intended to cooperate selectively with a second friction surface of a second element, wherein articulation means, on the one hand, and sealing means, on the other hand, are respectively disposed axially between a proximal bearing face of the first element and a distal bearing face of an adjacent element, and wherein the first element and the adjacent element, which extend radially, orthogonally to the main axis, are rotationally connected by connecting means adapted to transmit torque between said elements.
2. Description of Related Art
The document DE 102006048499 A1 describes a hydrokinetic coupling device including one embodiment of such a lock-up clutch provided with associated articulation and sealing means.
In that document, the lock-up clutch includes a first element formed by a disk, called the support disk, having a first friction surface which, being part of a friction facing fastened to the disk, is intended to cooperate, in the operating position (clutch engaged), with a second friction surface of a second element.
The second friction surface, axially facing the first, is globally parallel to the radially oriented first friction surface.
In the case of a clutch of the “single-sided” type (FIGS. 1 and 2), the second element is one of the shells of the casing, an annular portion of the wall of which forms the second friction surface.
In the case of a lock-up clutch of the “two-sided” type (FIG. 3), the second element is a friction disk that is disposed axially between the first element and the shell of the casing and has two friction facings.
Accordingly, the radial face of one of the friction facings forms the second friction surface intended to cooperate with the first friction surface of the first element whereas the radial face of the other friction facing forms a third friction surface intended to cooperate with a fourth friction surface formed by an annular portion of the wall of the shell of the casing.
In each of the above types of lock-up clutch, the support disk forming the first element is rotationally connected to an adjacent element formed by a piston.
The support disk has a proximal bearing face that is axially opposite the face carrying the friction facing and extends radially, globally parallel to a facing distal bearing face of the piston.
The support disk includes articulation means that project axially from the proximal bearing face and cooperate with the distal bearing face of the piston to form an articulation adapted to allow relative movement between the support disk and the piston.
Sealing means in the form of a lip seal are arranged between the proximal face of the support disk and the distal face of the piston to provide the seal required for axial movement of the piston from its rest position (clutch disengaged) to its operating position (clutch engaged).
In the above document, the support disk forming the first element is rotationally connected to the piston forming the adjacent element by meshing connecting means. To be more precise, the support disk includes lugs that extend axially through the piston, which to this end includes complementary housings into which the driving lugs penetrate.
However, such connecting means are not entirely satisfactory, for various reasons explained hereinafter.
With such meshing rotational connecting means, the cooperation of shapes between the lugs and the housings is necessarily effected with some radial and/or axial play to retain the possibility of movement of the support disk relative to the piston via the articulation means.
Consequently, movements of the support disk relative to the piston cause high friction at the connecting means formed by the lugs and the housings, which gives rise to problems of wear.
Moreover, such meshing connecting means are particularly costly to fabricate, notably because of the operations necessary to obtain the lugs and housings, or of the treatment applied afterward, for example to increase their hardness.